I had just finished building and testing my fourth 6502 build, a barebones testbed for my new PLD based address decoder. With my PLD successfully tested, the build didn’t really have much use anymore, except testing new PLD designs in the future. Given that it was barebones I figured it would be fun to see …
Continue reading “6502/65816: Running a 6502 build with a 65816”
I completed my fourth 6502 build the other day. It’s a barebones build, mainly intended to test my new PLD-based address decoding/interrupt request design. I didn’t need serial or keyboard support to test the PLD so haven’t included quite a bit of the I/O support that I had in build 3. I’m thinking that I’ll …
Continue reading “6502: My Fourth Build – Testing the New Programmable Logic Device”
I mentioned in my last post, Venturing Forth, that I ordered a programmable logic device to better refine my address decoding as my current circuit wastes about 16k on I/O. I worked up the new memory map and PLD files while waiting for the device to arrive. Then, as seems all too common with me, …
Continue reading “6502: Programmable Logic Devices – Address Decoder Revisited”
My first 6502 build, which followed Ben Eater’s 6502 computer project, uses two pretty pedestrian memory chips, an Atmel AT28C256 32k byte EEPROM and a 62256 32k byte SRAM. The EEPROM has a relatively slow 150 nanosecond access time. The SRAM access time is faster at 70 nanoseconds. The significance of these access times become …
My first 6502 build, which followed Ben Eater’s 6502 computer project, has a 16 character by 2 line LCD and a single red LED for output and four push button switches for input. Ben stopped his original video series with just a single push button, but I added three more as pictured on the front …
The 6502 microprocessor can address a 64k byte range. As a system designer you must split this address space between RAM, ROM and I/O according to your requirements. My first 6502 build, which followed Ben Eater’s 6502 computer project, used a straight forward memory map with 16k bytes of RAM (address range $0000-$3FFF), 32k bytes …
The WDC65C02 datasheet says that to initialize the microprocessor and start program execution the reset pin must be held low for at least two clock cycles after the power supply reaches operating voltage. In most cases if this is not done your 6502 based computer will not function properly. Ben Eater’s 6502 computer accomplishes this …
I enjoy recreating the component tests that Ben Eater performs in his electronics project videos. Sometimes my test results differ enough from Ben’s that I wonder if the component I’m testing is defective. More often than not the component is fine and I’ve either botched the test circuit or have set up the testing equipment …
Continue reading “6502: Is My Crystal Oscillator Working Correctly?”
For the last six months or so of Covid lockdown I’ve been having fun following along with and expanding on Ben Eater’s breadboard computer projects. They are great educational projects and I’ve learned a lot of computer fundamentals along the way. There is also a subreddit with lots of helpful people and advice on building …